Compared to Last Season ... (Part 1: Pitchers)

Last week I devoted a pair of entries to examining how the Twins fared through exactly one half of the schedule, looking at the pitching staff on Tuesday and the lineup on Thursday. The entries focused on the team as a whole, but with the All-Star break leaving us without games to watch I'd like to take this opportunity to delve a little deeper into the performances of individual players. Specifically, comparing how each player's first-half performance this year compares to their season totals from last year.

Today I'll tackle the pitchers and later this week I'll cover the hitters. Rather than a focus on stuff like win-loss records and ERAs, which often leave a lot to be desired, what you'll see quoted instead are more advanced metrics that attempt to break down a player's performance in a more detailed and complete manner. In other words, rather than simply saying that a pitcher is 6-3 with a 4.50 ERA, these numbers will help show how they got there. Here's a quick list of the metrics I'll be using:

xFIP - Expected Fielding Independent PitchingSO% - Percentage of plate appearances ending in a strikeoutBB% - Percentage of plate appearances ending in a walkHR% - Percentage of plate appearances ending in a home runGB% - Percentage of balls in play that are ground ballsBIP - Batting average on balls in play

Already one of the most extreme fly-ball pitchers in baseball, Johan Santana has induced even fewer ground balls this season. Fly balls are typically easier to convert into outs than ground balls, which is why his batting average on balls in play has improved from .269 to .256. However, fly balls can also leave the ballpark, which is why he's served up a homer about 35 percent more often. The end result is that Santana has been slightly less effective, especially considering the league-wide drop in offense.

However, his strikeout rate remains outstanding (only Erik Bedard can top it among AL starters) and Santana's tendency to thrive in the second half is obviously well documented. He's been one of the five best starters in the league during the first half and heads into the All-Star break having gone 4-0 with a 1.54 ERA over his last five outings. With a little better run support--the Twins scored three or fewer runs in 10 of his 18 starts--Santana could easily make a run at his third Cy Young award.

The general perception seems to be that Boof Bonser has been a disappointment this season, but his overall performance has actually been better than last year in several key spots. For one thing, he's upped what was already a very good strikeout rate, whiffing 20.7 percent of the batters he faced in the first half to rank 13th in the league. Along with that, he's induced more ground balls and, in turn, done a better job keeping the ball in the ballpark.

He's struggled with control, where a 50 percent increase in walks has often kept Bonser from working deep into games and feeds into the idea that he's taken a step backward. However, a big part of his quasi-struggles comes from a .321 batting average on balls in play, which is significantly worse than Bonser's .294 mark last season and suggests that he's likely been a bit unlucky. Bonser's 4.16 xFIP ranks 19th in the league, one spot behind Dan Haren and one spot ahead of Justin Verlander.

Carlos Silva has sliced his ERA from 5.94 to 4.58, but his xFIP suggests that the gap in his overall performance hasn't been quite that huge. However, there's little doubt that Silva has improved significantly this season, upping his strikeouts by 14 percent and keeping the ball on the ground eight percent more often, which has helped him cut the homers allowed in half. His walks have gone up nearly 30 percent, but Silva's walk rate still ranks ninth among AL starters.

He's still not even close to an extreme ground-ball pitcher (despite what Bert Blyleven repeats a dozen times during each of Silva's starts), but Silva has at least gotten back to having an above-average ground-ball percentage after spending last season as a fly-ball pitcher. Silva has statistically been somewhat lucky when it comes to fly balls not leaving the ballpark, but if yesterday's outing against the White Sox is any indication that could quickly even out in the second half.

Last season, Scott Baker was about as extreme a fly-ball pitcher as there is and because of that it's not surprising that he served up 17 homers in 83.1 innings. He's still very much a fly-ball pitcher, but Baker has induced 17 percent more ground balls this year while slicing his home-run rate by 20 percent. In other words, for all the talk of needing to "keep the ball down," he's done exactly that. Along with his typically solid strikeout and walk rates, that adds up to a very good pitcher in terms of xFIP.

Why doesn't his 5.71 ERA match his 3.96 xFIP? For one thing, Baker's .323 batting average on balls in play is higher than you'd expect from an extreme fly-ball pitcher. Beyond that, his percentage of fly balls that have turned into homers is very high and his percentage of runners stranded on base is very low, both of which figure to improve. Baker's first half has been filled with great starts and horrible starts, and the inconsistency could play a part in his mismatched numbers given the small sample size.

With a 2.17 ERA and 16 saves in 18 chances, Joe Nathan had a fantastic first half. However, his strikeout rate is down 25 percent and his walks have risen 30 percent. Those are concerning signs for a 32-year-old closer, although he still ranked ninth among AL relievers in strikeout rate and the lone "homer" he gave up was courtesy of a Lew Ford misplay. Despite not serving up a single legitimate homer in 37 innings, opponents have hit .250 off Nathan after batting just .158 against him last year.

The reason is a .340 batting average on balls in play, which is a very high number to begin with and becomes even more amazing when you consider that he allowed a measly .238 batting average on balls in play last season. The good news is that a .340 average on balls in play isn't likely to last very long (just like a .238 average on balls in play wasn't sustainable long term), so many of the bloopers and choppers that went for hits in the first half should begin to dry up.

Beginning with a 1.70 ERA and .129 opponent's batting average, Pat Neshek's first half was filled with amazing numbers. On a staff with extreme fly-ball pitchers like Santana, Baker, and Nathan, Neshek stood out because only seven AL pitchers with at least 25 innings had a lower ground-ball percentage. He also ranked third in strikeout rate, behind only Jonathan Papelbon and Francisco Rodriguez, and led all of baseball with a ridiculously good .149 batting average on balls in play.

Fly balls and strikeouts is a combination that leads to a low average on balls in play, but .149 is completely unsustainable. Even with regression coming, Neshek is clearly among baseball's elite relievers. As a side-arming right-hander with extreme fly-ball tendencies he's relatively vulnerable to left-handed bats and homers, but those vulnerabilities have been vastly overstated. He's allowed 11 homers in 79 career innings, which is far from an alarming rate, and has held lefties to .176/.245/.353.

Once the Twins' long reliever, Matt Guerrier has claimed a prominent late-inning role this season thanks to Jesse Crain's injury, Juan Rincon's struggles, and a 1.70 ERA. No pitcher in baseball with at least 50 innings turned in a lower first-half ERA and Guerrier has shown major improvement in the form of a 48-percent increase in strikeouts, along with fewer walks and more ground balls. However, Guerrier's underlying numbers suggest that he's also been quite lucky.

For starters, a .216 batting average on balls in play is unsustainable long term and sticks out like a sore thumb when compared to his .290 average on balls in play heading into this season. Beyond that, he's sliced 67 percent off his home-run rate after being somewhat homer-prone in the past, which is due to just 4.2 percent of his fly balls going over the fence. The league average is about 11 percent, which is why Guerrier's xFIP is more than double his ERA.

Rincon's performance has steadily declined on an annual basis since 2004 and this season's deterioration has made it clear that he's no longer an elite setup man. Rincon's strikeouts are down, his walks are way up, and he served up five homers in 31.2 first-half innings after allowing a grand total of four homers in 151.1 innings between 2005 and 2006. Not only has Neshek taken over his former role as Nathan's primary setup man, Guerrier has also passed him on the late-inning hierarchy.

Given his decline, it says a lot about how dominant Rincon once was that he still misses enough bats and gets enough ground balls to avoid being a liability. With that said, if the Twins decide to trade some pitching for a much-needed upgrade offensively, Rincon is seemingly the first guy to shop. At 28 years old and with three straight seasons of decline a major bounceback isn't likely, and the Twins aren't lacking in capable middle-relief options. His yearly xFIP beginning in 2004: 3.15, 3.32, 3.73, 4.66.